This invention relates to dental resin compositions comprising polymerizable (meth)acrylate resins, their method of manufacture, and the use of such resins for restorative dentistry, including dental adhesives, dental cements, dental filling materials, root canal sealants, crown and bridge materials, and the like.
In recent years, materials used for dental restorations have principally comprised acrylate or methacrylate resins. Resinous materials of this type are disclosed, for example, in U.S. Pat. No. 3,066,112 to Bowen, No. 3,194,784 to Bowen, and No. 3,926,906 to Lee et al. An especially important methacrylate monomer is the condensation product of bisphenol A and glycidyl methacrylate, 2,2′-bis[4-(3-methacryloxy-2-hydroxy propoxy)-phenyl]-propane (“BisGMA”). Alternatively, BisGMA may be synthesized from the diglycidyl ether of bisphenol A and methacrylic acid (see, e.g., U.S. Pat. No. 3,066,112 to Bowen).
Because the wear and abrasion characteristics and the overall physical, mechanical, and optical properties of these unfilled acrylic resinous materials is poor, and because acrylic resin systems exhibit high coefficients of thermal expansion relative to the coefficient of thermal expansion of the tooth structure, these substances by themselves are less than satisfactory. In particular, the disparity in thermal expansion coupled with high shrinkage upon polymerization results in poor marginal adaptability, and ultimately leads to secondary decay. Composite dental restorative materials containing acrylate or methacrylate resins and fillers were thus developed. The fillers are generally inorganic materials based on silica, silicate based glasses, or quartz. These filled compositions are useful for a variety of dental treatments and restorative functions including crown and bridge materials, fillings, adhesives, sealants, luting agents or cements, denture base materials, orthodontic materials and sealants, and other dental restorative materials. Despite their suitability for their intended purposes, however, many of these materials have shrinkages of about two to about four percent by volume upon polymerization.
There accordingly remains a need in the art for dental resin materials that have good bonding adhesion to a dental substrate and minimal shrinkage upon polymerization without sacrificing other advantageous physical properties.